Yes but I'm also surprised by that.
Anytime I create a new user, and I send a mail to the user with a subject,
If the user is trying to reply the the mail, the subject field is
blanc and the user have to fill it manually.
which is not normal.
I have been struggling myself since 2 weeks to fine the cause of the problem.
I have a signature filled and I do not have the same problem. So when
a User fill a signature in the settings, all work fine. But even if
there is no sgnature, the fact that the user click on "Save" in
/services/prefs.php?app=imp&group=identities
it also work fine.

So I really not understand that and I think that there is something
going wrong somewhere.

Paul

I don't understand what you are saying.

There is no "subject" setting in the identities.

And the subject is created from the subject of the replied-to
message anyway. It's not something that can/should be statically
configurable.

When replying to a mail, the subject field is empty.
I have discovered that if I go to Mail->Preferences->Personal
Information->Save ,
then the problem is solved. Meaning that each user must go to his
Mail->Preferences->Personal Information-> then click on Save to allow
his subject to appear when replying to a mail.

Thank you to look at it or is there any solution at administrator
level to solve that issue for all users?